[#559] docman: Unable to empty trash

Steps to reproduce: 1) Create a new project 2) Import the phpwiki ZIP (in attachment) in docman (will stop on a title length error, no worry). 3) Put the whole phpwiki folder in the trash 4) Clean the whole trash

Trash cleaning will fail with SQL errors (not visible): [256] SQL error: DELETE FROM docgroups WHERE stateid=$1 AND groupid=$2 AND groupname !=$3 [256] SQL: Arguments=["2","7",".trash"] [256] SQL> ERROR: update or delete on table "docgroups" violates foreign key constraint "docdatadocgroupid" on table "docdata" DETAIL: Key (docgroup)=(35) is still referenced from table "doc_data".